In a conventional tractor feeder which typically comprises a pair of tractor feeder units, pins projecting from a pin belt which is passed along the upper surface of each of the tractor feeder units are engaged to the perforations provided along side edges of the printing paper so as to pull the paper, as the pin belt is driven along the upper surface of the tractor feeder unit, after the paper is passed around a platen. However, there is a demand for reversing the paper feeding direction, for example for graphic printing purposes. Additionally, depending on the applications, it is desirable, instead of pulling the printing paper from the platen, to push the printing paper by the means of the pins, which are engaged with the perforations of the printing paper, towards the platen, and, alternatively, to both push and pull the printing paper towards and away from the platen by using the upper and the lower surfaces of the tractor units. A conventional paper feeder for a printer is capable of only one of the above mentioned three modes of paper feeding and it has been necessary to change the paper feeder when the mode of paper feeding is to be changed.